A type of man-made substance known as a synthetic polymer is made up of networks and chains of repeating units. Examples of common materials include polyacrylate (such as adhesives), polyester, polyvinyl chloride (PVC), polyamide (such as nylon), and polyethylene (PE) (e.g., PET). You'll discover that synthetic polymers are used to create a sizable fraction of the items in your daily life. Without synthetic polymers, we wouldn't have laptops, phones, bottles, different types of textiles, and so much more.
Figure 1: Example of everyday objects that are made from synthetic polymers.
The formation of any polymer follows the same basic steps: first, many molecules of the same kind, also known as monomers, are accumulated, and then these monomers join together to create long chains and extensive networks. In a general sense, there are two methods by that monomers can bond to one another: addition polymerization and condensation polymerization. In addition, polymerization, the combination of monomers, does not result in the formation of any by-products. Condensation polymerization is a process in which monomers combine while simultaneously expelling smaller molecules, such as water, during the reaction.
By adding more polymers, additional polymers are created. Like domino bricks falling on top of one another and starting a chain reaction, additional polymerization occurs. Each monomer must have a double bond, with one of the two bonds being more delocalized and simple to break, for such a chain reaction to take place. A free radical, or unpaired electron, breaks a double bond to pair with another electron, starting the addition reaction. But this results in a fresh unpaired electron, which sets off a chain reaction where the process keeps happening. The length of the polymer chain increases with the duration of this reaction. This keeps happening until two free radicals team up, a termination reaction occurs, and the polymer chain ends because there are no unpaired electrons left.
Figure 2: The main steps of addition polymerization.
Condensation polymerization differs from addition polymerization in two ways: 1) no initiator is required for the process to begin, and 2) a tiny molecule, such as water, develops as a byproduct. Condensation polymers are those in which two different types of monomers alternately link, such as polyesters (like PET) and polyamides (like nylon). A molecule with two amine groups and a molecule with two carboxylic acid groups interact to form nylon. Amido groups are created while water is released during the reaction.
Figure 3: Condensation polymerization between an amine and carboxylic group, forming an amide linkage.
Polymers' characteristics, including the kinds of monomers and cross-links that may be present, are determined by their chemical structure. For instance, the polymer's hydrophilicity (or love of water) is influenced by the polarity of the monomer. On the contrary hand, the stiffness of the polymer chain is influenced by the form of the monomer and how easily it bends. Cross-linking is joining adjacent chains, which changes the material's viscosity, strength, hardness, and melting characteristics. For instance, boric acid in slime increases the number of cross-links between chains, transforming the liquid into a viscous cohesive material. Another instance of cross-linking is Kevlar®, where the nearby chains are linked together like a web by powerful hydrogen bonds. We use this web for bulletproof vests since it can withstand a lot of stress.
Figure 4: The chemical structure of some synthetic polymers.
The capacity of many synthetic polymers to withstand many types of chemical and physical degradation is their most valued quality. Synthetic polymers, however, maintain their structural integrity long after serving their intended purpose because of the same feature. Think about a hamburger: it lasts for about a week, but the plastic wrap can last for 20 years! This distinction raises environmental concerns because the wrapping may find up in places it shouldn't, like a turtle's gut. In landfills, certain plastic products can potentially last a thousand years! Imagine if our burgers were instead covered in polymers with a reduced lifespan.
Why are synthetic polymers a hard topic for students?
1. A lack of fundamental information
Students will have trouble studying polymers if they don't have a basic understanding of them. Determine the level of their fundamental knowledge and alleviate their concerns first. Tell them about polymers' primary use, applications, and differences between natural and manmade polymers. First, go over the fundamentals and then explain how a chemical reaction happens.
2. You must depict intricate response structures.
Chemistry reactions are a time-consuming and uninteresting subject that students detest learning about. Students studying polymers' rules must not only recall the reactions but also depict the intricate interactions between the compounds. Certain reactions can be finished in a single step. But some chemical reactions take several steps to complete. These are crucial because they can facilitate the conversion of reactants into products.
3. It presents conceptual difficulties.
Theoretical modeling of polymers is challenging due to the reactions involved in this process. The kids can be perplexed as to how and why the arrangement was formed as a result. You can use your laptop to demonstrate the process and the photographs, but this takes more time. Video graphics is, therefore, a better learning tool.
Five ways to teach Synthetic Polymers: Discover their impact on everyday life
1. Learn about physical properties
There are three fundamental types of physical polymer structures: cross-linked, branching, and linear, that students should learn.
Since linear polymers have lengthy monomer chains, they resemble spaghetti. Weak intermolecular forces are what connect the chains together. This trait, known as thermoplasticity, allows us to remold the material since it quickly breaks and reforms these weak connections after further heating and cooling.
Branched polymers have side chains that are either shorter or longer than the long linear backbone. These side chains displace nearby chains, decreasing density more than linear polymers. Most branched polymers are thermoplastic, but others may contain branching that is so intricate that it tangles and prevents melting, a property known as thermosetting.
Cross-linked polymers are those in which the neighboring chains or branches have strong connections to one another. Cross-linked polymers are thermosetting because the cross-links are robust and prevent relative movement between the chains.
2. Applications of synthetic polymers
Due to the great variety of chemical and physical structures that synthetic polymers can have, their qualities can be adjusted and controlled in a variety of ways. As a result, we can put them to many different uses. Our lives would be entirely different without synthetic polymers.
Teflon: The polymer can endure disruptive forces, such as chemical attacks and high temperatures if strong links hold the monomers together. One polymer with robust bonding is PTFE (Polytetrafluoroethylene), also known as TeflonTM. Even though it is based on the straightforward monomer C2F4, the C-F bond is one of the strongest single bonds in chemistry! Fluorine atoms are evenly distributed across the polymer chains, resulting in strong bonding as well as a consistent hydrophobic surface that repels water. These chemical characteristics make TeflonTM ideal for coating cooking plates and rendering them non-stick when taken together!
Nylon: Thermoplastic polymers, such as nylon, melt when heated. A polymer needs long chains drawn to one another by weak intermolecular interactions to be thermoplastic. Nylon is a type of thermoplastic polymer. A condensation polymer labeled nylon is created from two different kinds of monomers. Amido groups are created when the monomers polymerize. These amide groups provide the fibers with their hydrophilic properties and cause hydrogen bonds to form between neighboring fibers, giving them a high tensile strength.
Kevlar®: Cross-linking strengthens polymers by limiting the relative movement between polymer chains. Cross-linked low- and high-density epoxy adhesives (polyacrylate), polyethylene (XLPE and PEX), and Kevlar® are a few examples of cross-linked polymers. Kevlar® is a condensation polymer created when two monomers with benzene rings are polymerized. Long chains of connected benzene rings are the end outcome. In addition to having a high tensile strength ten times stronger than steel, Kevlarchains ®'s cross-link with hydrogen bonds provides exceptional toughness, heat, and chemical resilience. Despite this, it is still lightweight and ideal for boats, light body armor, vehicle breaks, and aeronautical engineering.
3. Natural v/s Synthetic polymer
Students often confuse or consider both of them the same. Giving them a clear idea is important. Scientists and engineers use petroleum oil to create synthetic polymers. Nylon, polyethylene, polyester, Teflon, and epoxy are some examples of artificial polymers. It is possible to extract natural polymers from the environment. They frequently consist of water. Silk, wool, DNA, cellulose, and proteins are naturally occurring polymers.
4. Seeing is Believing
When students see color diagrams, their interest in learning increases. Students can better understand complex subjects like polymers thanks to the variety of hues. Because they are easy for students to memorize, color diagrams aid in learning. Students must learn about several reactions and molecular structures when studying chemical reactivity. When kids encounter colored visuals, it may be beneficial for them to recall these emotions and structures.
5. Utilizing virtual lab simulation
With the advancement of technology, using simulations to teach difficult and complex processes has become simpler. You may now simulate tests without using any expensive equipment. You can enlist the aid of Labster's virtual lab simulations in this regard. Through interactive learning settings, these simulations hold students' attention. Students immerse themselves in a 3D environment where they can learn concepts graphically and apply them to solve problems in the actual world. Check out Synthetic Polymers: Discover their impact on everyday life Virtual Lab.